1. Field of the Invention
This invention relates in general to internal combustion engines, and in particular to any engine or device which utilizes a dipstick to verify fluid reservoir levels.
2. Prior Art
Checking the fluid levels in an internal combustion engine is an essential part of regular preventive maintenance. Incorrect levels, both above and below optimum, can shorten the useful life of an engine dramatically. Due to its simplicity and accuracy, the dipstick remains in wide use to verify such fluid levels. By its nature, however, the dipstick must be wiped clean with another material before a fluid level check can be performed. Prior attempts to develop a self wiping mechanism for the dipstick have resulted in cumbersome, overly elaborate, or inconvenient devices. Although each of these devices satisfies the desired function of wiping the dipstick, none to date equalls the compact, maintenance free convenience of the present invention.
U.S. Pat. No. 4,233,704 to Sartorio describes several variations of a dipstick cleaning device, both attatched to the dipstick entrance tube, and mounted remotely elsewhere. Designs shown are elaborate, and are therefore costly to produce and difficult for the novice to operate. All designs shown incorporate absorbent pads, which, when saturated, would require periodic cleanings or replacement. Such pads would also be prone to collect road debris and grime. One version employs a separate collection tank for wiped fluids, which must be drained when the tank nears its capacity. This further complicates an already complex device by adding another required maintenance step.
U.S. Pat. Nos. 4,422,204 and 4,506,402 to Long, Jr. describe a dipstick cleaning device which mounts directly to the dipstick entrance tube. Like the Sartorio device, this device employs absorbent pads which must be periodically cleaned or replaced. It too is mechanically elaborate, and would therefore be costly to produce and difficult for the novice to operate. As shown, this device requires the user to use both hands; one to pull out the dipstick, and one to pinch the wiper pads together for the cleaning sequence. As will be shown for the present invention, such additional steps are incovenient and unnecessary.
U.S. Pat. No. 4,658,462 to Elassar describes a remotely mounted dipstick cleaning unit. When mounted somewhere in the engine compartment, this device does offer a means of wiping the dipstick without a separate wiping material. Like the Sartorio and Long, Jr. devices, however, this device requires periodic maintenance in of itself. Fluids removed by the device's opposing wipers accumulate inside the unit, and must be drained as the unit nears capacity. Like the Long, Jr. device, this unit requires two handed operation. Also, given the complexity of late model engine compartments, the question of where to mount a remote unit becomes inescapable.
U.S. Pat. No. 4,780,925 to Sherman depicts an automatic dipstick wiping device which mounts directly onto the dipstick entrance tube. It employs a single block of wiping material, such as foam rubber, which acts to clean one side of the dipstick as the dipstick is withdrawn from the tube. By cleaning only one side of the dipstick, this device invites human error into the fluid level check. As pictured, this block is mounted in an exposed position, where dirt and contaminants are sure to accumulate. Although less elaborate than the previously cited devices, this device could also prove harmful to the engine, if dirt and contaminants find their way down from the wiper block to the tube and reservoir below.
U.S. Pat. No. 4,860,401 to Deveaux offers a workable solution to the dipstick cleaning problem. With this device, a fixed stopper encloses the upper end of the dipstick entrance tube. Two slit apertures open through the stopper to allow the dipstick access to the fluid reservoir below. One of the apertures is large enough to allow the dipstick to pass through without being wiped clean. The other is small enough to wipe the dipstick clean as it passes through. Wiped fluids return to the entrance tube and reservoir, and there are no absorbent pads to clean or replace. The chief drawback of this device is that it requires the user to discern between the two slit apertures. Especially in a dark or dimly lit engine compartment, this action would become difficult at best. Also, in order for the dipstick-mounted cap to close over the device with the dipstick inserted in either aperture, the inner cap diameter must be substantially greater than the outside diameter of the stopper. This loose fit of the cap would encourage road grime and contaminants to enter the device, and ultimately the reservoir below. Although simple in design, the Deveaux device is both inconvenient to use, and potentially harmful to the engine it serves.